Automatic slack adjuster for brake rigging



ug. 4, 1931. E. J. JoNAs AUTOMATIC SLACK ADJUSTER FOR BRAKE RIGGING 12.57024 Avv. I I

Original Filed Feb. 22, 1929 A TT ORNE Y.

Patented Aug. 4, 1931 PATENT OFFICE EMIL J'. JONAS, OF CINCINNATI, OHIO AUTOMATIC SLACKIADJU'STER FOR BRAKE RIGGING Application filed February 22, 1929, Serial No. 341,860. Renewed November 28, 1930.

This invention relates to improvementsin Y slack adj usters and more particularly to automatic slack adjusters adapted to be used in A connection with the truck brake rigging of street cars, although, of course, it is to bey understood that certain features thereof are applicable to other types of brake rigging aside from that shown in the drawings.

The objects of the `present invention are to 0 provide an automatic slack adj uster for brake rigging which is simple, efficient, economical to manufacture, the operating parts of which are entirely enclosed and can be kept thoroughly lubricated at all times; an adjuster that automatically provides the necessary brakeshoe clearance; and yan adjuster that weighs less than one-half of any of the pres-y ent slack adjusters, ywithout sacrificing strength or efliciency. f

Another object of this invention is to provide an automatic slack adjuster of simple construction which cannot be tampered with or improperly, adjusted.

Still another object of the present invention is to so construct a slack adjuster of the screw type which cannot fail in service in such a manner. as tol allow the brakes to fail.

Other objects and Vadvantages to be hereinafter pointed out are attained by that certain novel construction and arrangement of partsillustrated in the 'drawings in which I have shown the preferred embodiment of my invention. I

Iny the drawings: y

Fig. 1 is a sidevelevational view showing such parts of a truck and associated brake rigging as, is necessary to understand the present invention; n .Y

Fig. 2 is a vertical longitudinal section of the'invention, parts appearing in elevation;

Fig. 3 is a cross section taken onA the line 3 3 of Fig. 2 and Alooking in the direction of the arrows;

Fig. 4 is an end view of one vof the clutch members;

Fig. 5 is a fragmentary section on the line 5-5 of Fig. 1, parts appearing in elevation; and

Fig. 6 is a cross section on the line 66 of Fig. 2.

In the embodiment of my invention as illustrated and which shows a preferred construction l designates a truck framework of the usual construction, which is of the four wheel type, and having wheels 2 2 on each f side adapted to be engaged by brake shoes 3 in the well-known manner.

These brake shoes are carried by brake heads 4 pivotally connected at 5 and (5 to live and dead levers 7 and 8, respectively. The upper end of live lever 7 is connected by means of pull rod 9 with any suitable source of power, while the upper end of dead lever 8 is pivotally mounted at 10 to the framework 1.

The aforementioned parts are all of the usual and well-known construction, my invention however residing only in the member 11, pivotally connected between the lower ends of the live lever 7 and dead lever 8. This member 11 comprises a two part telescopic push rod and its purpose is to automatically take up the slack between the lower ends of the live and dead levers due to wear in the shoes and other parts.

Referring now to the member 11 in detail.

"and more particularly to Fig. 2, 12 designates an elongated tubular member which is telescopically received within elongated tubular member 13. The outer end of tubular member 12 is closed by a bifurcated link 14, the stud end of which is securely fixed within the end of said member 12 by a rivet pin 15. The inner end of tubular member 12 receives a sleeve 16, which is held therein by a. forced fit and is provided with a threaded hole 17 l extending lengthwise therethrough.

A screw 18, provided on its outer periphery with threads 19 of great pitch, is adapted to be received by threaded hole 17 in plug 16,

one end of said screw having` a clutch member 20 fixed thereon and the other end being rotatably received by ball bearing 21 slidably carried within tubular member 12. yCup 22 abuts with bearing 21 and receives one end of expansion spring 23, the other end of which spring bea-rs against the inner surface of thestub end of bifurcated link 14.

The outer end of tubular member 13 is closed bv bifurcated link 24, the stud end 24 of which is securely lined within the end of stud end 24 of bifurcated links 24 and is nor# mally heldtherein by the pressure of stemV 28, as'will be explained more fully under opu Y erationsof the device.

l- 31 designates a split sleeve which is adaptedto frict-ionally embrace and engage the outer periphery of tubular member v13, said sleeve being. provided with an arm 32 pivotally connected at V to live lever 7, as shown in'Fig. 1. f

In operation, whenv the upper end of. 'live lever 7 (pivoted' at 5) is pulled towards the left :in the direction. of the arrow A by pull rod 9, the lower'endof said live lever moves tow rds the right and, through the member 11, coacts with thelower end of dead lever 8 to carryrthe brake shoes 3 into engagement withA the pcripheries of the wheels 2. After the shoes 3 become worn to such an extent as to allow an excessive clearance between the wheels and said shoes the member 11 is'automatically lengthened 1n the following manner: lVhen the brakes are released the pull rod 9 and live lever 7 returnto the inoperative position (asl shown inFig. 1), at which j time the split sleeve 31 will havea tendency to move the tubular member13 outwardlyupon tubular member 12, thereby causing the distance to take up the slack between live lever 7 and dead lever8whereupon the teeth 26 of clutch member 2O will again be engaged withthe teeth 27 of stud end 24 vof bifurcated link Vhen there is yno need for length-` 'ening the member 11 the split sleeve 31 merely. slides over the outer periphery of tubular member 13, Vits action against said tubular member being only necessary during 4the slack take-up period. This take-up means, represented Aby the spring 23,scr ew` 18, and clutch member 20, automatically acts whenever the ' shoes 3A become sufficiently worn to permit the y Gil separationl ofyvclutch teeth 26 `from clutch teeth 27 and continues to act until the brake shoes3 are entirely worn out. Then, to ap lply new shoes the clutchfmember 20 may be disengagedfrom the stub end 24 of bifurcated link 2li in order to collapse the member 11.

Toldo this nllthat is necessary for the oper-` ator to do is to insert any convenient tool upon one end of pin 29 and drive said pin inwardly a sufficient dist-ance to force the reduced stem 28 (of screw 18) outwardly a suflicient distance to disengage clutch teeth 26 from the clutch teeth 27 at which time the tubular member 12 may be pushed within tubular member 13 against the pressure of 'expansion spring 23. The entire available space within tubular members 12 and 13 can be filled with grease or oil to thoroughly lubricate the working parts carried within said Vvmembers, which lubricanty will protect all of said working parts, and, due to the construction of said members and working parts, foreign matter, such as dirt, dust, etc., will be prevented from coming into contact with said working parts and, therefore, the operation of lengthening the member 11. can be automatically taken care of Whenever necessary and under all conditions. u

I have found that friction sleeve 31 in some installations in my improved slack adjuster, may be omitted'without affecting the proper functioning ofthis device. The reason for this is that in such installationsthe lag, drag, or inertia inherent in the dead lever and its connected'parts is sutlicient to over-balance the frictional resistance existingibetween the telescopic members 12 and 13.v i

Anadvantage of. this invention isV that the working parts are Vfully enclosed within the tubular members 12 and 13, respectively, and thatno hand adjustment is necessary once themember 11 has'been pivotally connected to the lower end of live lever 7 and dead lever 8, respectively.

lt is believed that the above will so fully reveal, the gist of theA present invention that others can, by applying current knowledge, readily adapt the same to various uses and cmoditicationsj without departing from the scope `or spirit of theinvention as defined by the claims.

lVhat l claim as new by Letters Patent is:

automatic slack adjuster for brake mechanism comprising a two Ypart telescopic push rod, means within said push rod to permit lengthening.v and to prevent collapse thereof, said means comprising a spring, a feed' screw, rotatable Y,clutch member carried by saidH screw, a stationary clutchmember carried by said rod, anarm, a split sleeve attached to said arm, and frictionally mounted upon said rod for disengaging said clutch during the. slack take-up period.

"2. An Vautomatic slack adjuster for brake mechanism,said mechanism having live and dead levers, a two part telescopic push rodV comprising an elongated hollowmember, one end ofwhich is pivotally attached'to said live lever, a second elongated hollow member, onerend of which is privotally attached to said dead lever, and which telescopically and desire to secure ifo receives said rst-m-entioned hollow member, a two part clutch mounted within said last mentioned hollow member, a feed screw, a spring nested within said first-mentioned hollow member and adapted to normally hold said two part clutch in meshed engagement through said screw, and means frictionally engaging said secondmentioned hollow member and pivotally attached to said live lever to disengage `said two part clutch, for the purpose of lengthening said push rod.

3. push rod for brake mechanism having, in combination, live and dead levers, a hollow tubular member connected to one of said levers, a hollow tubular member con nected to the other of said levers and telescopically associated with said first-mene tioned member, and means carried within said hollow members adapted topermit relative movement of the members outwardly and prevent relative collapse thereof, for the purpcses specified.

4. An automatic slack adjuster for brake mechanism having, in combination, live and Vdead levers, a hollow two-part tubular tele-- scopic push rod connecting` said levers, a permanent take-up and holding means located within said rod and including a two-part clutch, a feed screw, a spring acting upon said feed screw tending to move it relative to the rod and a friction operating arm for progressively moving said take-up and holding means as the brake shoe or wheel wear occurs to thereby insure uniform brake shoe clearance.

5. In an automatic slack adjuster for brake mechanism, in combination, live and dead levers, a two .part telescopic push rod, a permarient take-up and holding means within said rod comprising a two part clutch and a feed screw co-acting with one of said parts, means acting upon the screw for holding said clutch parts in engaged relation, means for temporarily disengaging said clutch during the slack take-up period, and means for positively disengaging said clutch so the adjuster can be collapsed to permit application of new brake shoes.

6. An automatic slack adjuster for brake mechanism having live and dead levers comprising a tubular telescopic push rod, a permane-nt take-up and holding means located within said hollow rod and including a clutch, a feed screw, a spring and friction means for movin@` said take-up and holding means as the brake shoe or wheel wear occurs to thereby insure uniform brake shoe clearance, said friction means comprising a member having a yielding frictional engagement with the outer periphery of the push rod and movably connected to said live lever.

7. In an automatic slack adjuster for brake mechanism, in combination, live and dead levers, a telescopic push rod comprising an elongated hollow member, one end of which is pivot-ally attached to one of said levers, a second elongated hollow member, one end of which is pivotally attached to the other of said levers and which telescopically receives said first-mentioned hollow member, a clutch having a plurality of parts mounted within aid second-mentioned hollow member, a feed screw and a spring nested within said firstmentioned hollow member and adapted to normally held said clutch parts in meshed engagement through said screw, means in frictionally yielding engagement with said second-mentioned hollow member and pivotally attached to said live lever to temporarily disengage said clutch parts during the slack take-up period, and means for positively disengaging said clutch so the adjuster can be collapsed to permit application of new brake shoes.

8. In an automatic slack adjuster having a clutch and feed screw, means for positively disengaging said clutch comprising a pin reduced between its ends, said reduced portion adapted to normally receive the outer end of said feed screw when said clutch is engaged, said pin adapted to be moved outwardly to force the end of said feed screw away from said pin, thereby separating said clutch, lfor the purposes specified.

9. An automatic slack adjuster for brake mechanism, having in combination, live and dead levers, a two part telescopic push rod comprising' an elongated hollow member, one end of which is attached to one of said levers, a second elongated hollow member, one end of which is attached to the other of said levers, and which is telescopically associated with said first-mentioned hollow member, a two part clutch mounted within said second mentioned hollow member, a feed screw and a spring nested within said first-mentioned hollow member and adapted to normally hold said two part clutch in meshed engagement through said screw and prevent the collapse of said rod.

l0. An automatic slack adjuster for brake mechanism having, in combination, live and dead levers, a two part push rod comprising an elongated member one end of which is pivotallyattached to said live lever, a second elongated member one end of which is pivotally attached to said dead lever, a feed screw, a two part clutch one part of which is carried by said feed screw and the other part of which is fixed to 'one of said elongated members and a spring acting upon said screw to normally hold the parts of said two part clutch in meshed engagement.

1l. In an automatic slack adjuster for brake riggings, in combination, a live lever and a dead lever, an extensible rod comprising a pair of hollow telescopic members connected between the said levers against relative rotation, a toothed lclutch member mounted in onev telescopic member against .relative rotation thereto,a rotatable and longitudinally movable toothed clutch member to co-operate with the.. other clutch member and non-rotat- -able whenever in toothed engagement with said other clutch member, mechanism mounted in the other telescopic member and constantly acting to simultaneously advance and rotate the rotatable clutch member and advance it towards and into co-operative relationwith the nonrotatable clutch member, the clutch members rotatable relative to each other onlywhen disengaged and adjusting mechanism acting to move the telescopic members to extend the rod during the slack take-up period to adjust the rod for wear in the brake.V

12. In an V,automatic slack adjuster for brake rigging, in combination, brake levers, a

two-part telescopic push-rod connecting the levers,imechan`ism within said push-rod to permit'lengthening and to prevent sliertening thereof and comprising a feed screw and a nut therefor, a spring acting upon said screw and tending to advance the screw relative to the nut, a rotatable clutch member carried byjsaidV screw, a stationary clutch member carrie-d by said rod and co-acting with said rotatable clutch member and adjustable means exterior of said rodto eifect the lengthening of the'rod to take up wear in the brake rigging.

lfln an automatic slack adjuster for brake mechanism in combination, a two part telescopic push-rod, means within the rod to permanently extend and hold said Vparts comprising a screw rotatable and longitudinally movable relative to one telescopic part, a two part clutch having one part secured to the screw to rotate therewith and the other part Y secured to one telescopic part and non-rotatable relative to the screw and yielding means acting upon the screw and constantly urging the clutch part thereon into engagement with the otherclutch part. 1

f 14C. In' an automatic slack adjuster comprising, incombination, a live lever, a dead lever, an automatically extensible and ad-` justable push-rod connecting said levers, the rod comprising a pair oftelescopically associated tubular members having means at their kexposed ends to connect to said levers, a

l5. ,An automatic slack adjuster for brake rigging comprising, a power lever, a two-part telescopic push-rod, means within said pushrod to permit lengthening and to prevent vcollapse thereof, said means comprisinga screw,

la spring actingV upon said screw, a rotatable clutch member carried by ,sai-d screw, a stationary clutch member carried by said rod coacting with said rotatable clutch member, an arm connected to said power lever and means attached to said arm and having frictional yielding engagement with the saidV rod for disengaging said clutch during the slack takeup period. Y 1 f 16. An automaticy slack adjuster for brake mechanism, in combination, live anddead levers, a two-part telescopic push-rod comprising an elongated hollow member, one end of which is pivotally attached to one of'said levers, a second'elongated hollow member, one end of which is pivotally attached to the other of said levers, and whichtelescopically receives one end of said first-mentioned hollow member, a two-partclutch mounted within said second-mentioned hollow member, afeed screw and a spring nested within said firstmentioned hollow member and adapted to normally hold the parts of said two-part clutchiin meshed engagement through end pressure upon said screw and means having a yielding frictional engagement with said second-mentioned hollow member and attached to'oneof said levers to disengage the parts of said two-part clutch, for the purpose of lengthening said push-rod.

' EMIL J. JONAS.

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